The aim of the paper is to describe the influences of conventional and azimuthing podded propulsion on passenger ferry maneuvering, particularly turning circle and zig-zag maneuvers. The MATLAB-simulink program was used to simulate the turning circle and the zig-zag maneuvers. The program was developed based on the mathematical model for ferry maneuvering. The model involved the setting-up of a 4-DOF in a modular of the Mathematical Modelling Group (MMG) of the hull, propellers-rudder or pod system. The simulation includes separating components of the hull equations, propeller-rudder or pod systems as well as the interaction between them. The results indicated that the azimuthing podded propulsion has an advantage for turning circle performance, meanwhile conventional propulsion is beneficial for zig-zag maneuvers. The 1 st and 2 nd overshoot times of conventional propulsion of the sea trial are higher than the simulation; but the turning cirles of the sea trial are lower.
Cassia singueana (Delile) Lock from the family Fabaceae is a well-known medicinal plant that grows abundantly in Nigeria and other African countries, and has long been used in the treatment of various ailments including malaria and other infectious diseases. The present study aimed at assessing the composition, and bioactivity of the essential oil of the flowers of C. singueana collected from Nigeria. The essential oil was extracted by hydrodistillation and the chemical composition was analyzed by gas chromatography (GC) coupled with a flame ionization detector (GC-FID) and GC coupled to mass spectrometry (GC–MS). The bioactivity of the oil was determined using the brine shrimp lethality assay, agar diffusion antimicrobial test, the 2, 2-diphenylpicrylhydrazyl, metal chelation, and superoxide anion antioxidant assays. The essential oil yield and the percentage of identified compounds were 1.58% and 97.91%, respectively. More than 20 compounds were identified. The major component was geranyl acetone (36.82%) followed by phytol (18.12%). The essential oil showed lethality against the brine shrimp larvae with an LC50 value of 18.7 µg/ml, and antimicrobial activity with largest inhibition zones of 32-33 mm against Candida albicans, Streptococcus pneumoniae, and Staphylococcus aureus. The oil also exhibited considerable antioxidant activity as evident from its ability to scavenge free-radicals such as DPPH, superoxide anions, and metal-chelation.
Wind force and moment may force a ship to drastically decrease its speed and use a large drift angle as well as a large rudder angle in order to maintain its course. Ships with a small draught might have more risk in maneuvering to its point of view compared with a ship with a larger draught. This paper discusses maneuverability of a ship with a small draught in steady wind. The effect of wind on ship speed, drift angle, and rudder angle are investigated in a steady state condition. Five different ratios of wind velocity to ship speed from 1.0 to 20.0 are used in the simulation. The variation in wind direction is examined from 0° to 180°. Results of the numerical simulation show that the wind has a significant effect on the reduction in ship speed with a wind direction less than 100°. The drift angle increases due to increasing wind velocity in the same wind direction. Wind direction also has a significant effect on the drift angle especially when the wind direction is less than 140°. The same phenomenon was found for the rudder angle. The necessary rudder angle is greater than the maximum rudder angle of the ship when the wind direction is 60° with a wind velocity to ship speed ratio of 20 or more. AbstrakKemampuan Manuver Kapal dengan Sarat Kecil pada Kecepatan Angin Konstan. Gaya dan momen yang ditimbulkan oleh angin dapat mengakibatkan kecepatan operasi kapal berkurang secara drastis, sudut geser yang besar serta sudut kemudi yang besar untuk mempertahankan arah gerak kapal. Kapal dengan sarat yang kecil mempunyai kemungkinan yang lebih besar untuk mengalami masalah manuvering tersebut dibandingkan dengan kapal dengan sarat yang besar. Tulisan ini membahas performa manuvering kapal dengan sarat kecil pada kondisi angin dengan kecepatan konstan. Lima perbandingan kecepatan angin dan kecepatan kapal tersebut, yaitu 1,0, 5,0, 10,0, 15,0 dan 20,0 digunakan untuk simulasi. Arah data angin terhadap kapal divariasikan mulai dari 0° sampai 180°. Sudut geser kapal bertambah besar dengan bertambahnya kecepatan angin. Arah angin juga mempunyai pengaruh yang signifikan terhadap sudut geser khususnya pada sudut datang angin lebih kecil dari 140°. Fenomena yang sama terjadi pada kasus sudut kemudi. Sudut kemudi yang diperlukan untuk mempertahankan arah gerak kapal maksimum terjadi pada sudut datang angin 60° untuk perbandingan kecepatan angin dan kecepatan kapal (v/c) sama dengan atau lebih besar dari 20.0.
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